Starches are widely used in food applications as thickeners or bodying agents. They are unique among carbohydrates in occurring as discrete granules. In modern day food processing and storage applications, however, the properties of granular starch must be modified to withstand certain heat, acid and freeze-thaw conditions.
When granular starch is heated in excess water above the gelatinization temperature, it undergoes hydration and gelatinizes, forming a viscous solubilized paste. In practice, starch granules require dispersion in cold water before cooking at the time of use.
Recently, pregelatinized starch products have been developed that provide reconstituted pastes when mixed with hot or cold water. The starch manufacturer gelatinizes the granular starch and then dehydrates the gelatinized starch by such techniques as roll-drying or spray-drying and the like. Unfortunately, the dried pregelatinized starch product does not readily disperse in hot water and agglomerated masses are formed giving lumpy pastes with inconsistent paste viscosities.
Attempts have been made to circumvent the dispersibility problem by inclusion of surfactants with dried pregelatinized starch and somewhat improved dispersibilities were obtained as exemplified in U.S. Pat. Nos. 3,537,893; 3,582,350; 3,443,990 and 4,260,642. The effect of surfactants on starch pastes is also described by E. M. Osman In Starch; Chemistry & Technology, Vol. II, Chapter VII, pp. 189-191; Whistler & Paschall Eds., Academic Press, N.Y. (1967).
Free-flowing, agglomerated, heat-moisture treated starch products have been developed and used in food applications, as shown in Great Britain Pat. No. 1,479,515; U.S. Pat. Nos. 3,391,003; 3,578,497; 4,013,799; and German Reich Pat. Nos. 619,984; 629,798; 725,967; and 739,632.
The term "heat-moisture treated starch" is well known in the art and is commonly used to refer to a starch which has been subjected to a heat treatment under controlled moisture conditions, the conditions being such that the starch undergoes neither gelatinization (i.e. exhibits no substantial loss of birefringence) or dextrinization as discussed by Louis Sair in Methods in Carbohydrate Chemistry, Vol. IV, pp, 283-285, R. J. Whistler, Ed., Academic Press, N.Y. (1964) and by E. M. Osman in Starch: Chemistry & Technology, Vol. II, Chap. VII, pp. 179-181, Whistler & Paschall, Eds., Academic Press, N.Y. (1967). If heat-moisture treated starches are used in hot-water dispersible foodstuffs, dispersion of the mix into boiling water, nevertheless, results in formation of lumps and agglomerated or coated masses by surface gelatinization wherein a coating barrier forms on the starch preventing further hydration.
For improved convenience, a hot or boiling water dispersible starch product that consistently provides a uniform paste having no lumps or agglomerated masses associated therewith is desirable. A hot or boiling water dispersible starch thickener is particularly desirable for food products prepared in the home so that the consumer does not have to follow cumbersome cooking procedures often associated with the available starch containing sauces and gravies. In this invention, an improved starch-surfactant complex is provided that consistently provides complete dispersibility in hot or boiling water.
The combination of starch and gums or starch, gums and emulsifiers is generally known (see U.S. Pat. Nos. 3,917,875; 4,081,566; 4,081,567; 4,105,461; 4,119,564; 4,120,986; 4,140,808 and 4,192,900). The gums are used as thickeners or stabilizers in these formulations. Nevertheless, food formulations prefer to use as much starch as possible in these products due to the high cost of gums. The nature and use of gums is more fully described in Industrial Gums: Polysaccharides and Their Derivatives, Roy L. Whistler Ed., Academic Press, N.Y. (1959).
Starch derivatives have been developed for use in canned food products that require delayed gelatinization and resistance to heat, such as in cream style vegetables and for use in acid food systems, such as pie fillings, salad dressings and the like. Because of the severe acid and/or heat conditions encountered, these starch products were cross-linked and chemically derivatized to produce starch esters and starch ethers that were resistant to these conditions as disclosed in U.S. Pat. Nos. 3,238,193; 3,376,287; 3,422,088; 3,699,095; 3,555,009; 3,553,195; 3,751,410; 3,804,828 and 3,832,342. These products are expensive and require difficult preparation procedures.
It is highly desirable to have a starch-based product suitable for use as a food thickener in canned food products and acid food systems that would be both acid stable and heat stable. It is also desirable if the starch product at the same time possesses freeze-thaw stability. It would be most desirable if the starch-based food product having these properties could be made by a simple procedure that did not require expensive and cumbersome chemical derivatization of starch. In this invention a starch-surfactant-gum product which has these desired properties is provided by a simple physiochemical process.